The invention relates to a disc brake particularly for commercial vehicles, having a caliper straddling a brake disc, an application device arranged in the caliper for applying the brake, as well as an adjusting system arranged in the caliper for compensating brake pad and/or disc wear by adjusting the distance between the brake pad and the brake disc, wherein the adjusting system has at least one adjusting device.
The invention particularly relates to novel constructions of disc brakes, particularly for commercial vehicles, which are operated pneumatically and/or electromechanically.
According to the selected force introduction principle, disc brakes can be divided into two basic constructions:
1. Generating of force and wear adjustment on both sides of the brake disc: for example, the hydraulic fixed-caliper disc brake with an axially fixed brake disc and the generating of force on both sides of the brake disc, as well as
2. Generating of force and wear adjustment on one side of the brake disc and transmission of the actuating power to the side which faces away, according to the reaction force principle: for example, the sliding-caliper disc brake, the hinged-caliper disc brake, and the fixed-caliper disc brake with a displaceable brake disc.
Pneumatically operated disc brakes for heavy commercial vehicles with rim diameters of 15 inches and more normally use the reaction force principle since, because of the narrow installation conditions at the vehicle wheel, the arrangement of a compressed-air brake actuating cylinder can be achieved only on the side of the vehicle wheel which is open toward the interior side of the vehicle. Constructions of this type are found, for example, in German Patent documents DE 36 10 569 A1 and DE 37 16 202 A1, and European Patent document EP 0 531 321 A1 (see here particularly the construction of the adjusters in the manner of rotary drives), and European Patent document EP 0 688 404 A1.
Sliding caliper or hinged caliper disc brakes require a component fixed to the axle—generally called a brake anchor plate—which holds or guides the chocks/brake pads and absorbs their circumferential forces when the brake is actuated and carries the caliper disposed in a displaceable manner coaxially with respect to the vehicle axle.
The relative movement, which the caliper carries out with respect to the component fixed to the axle, can be divided into the working stroke and the wear stroke. The invention surprisingly utilizes this effect.
The working stroke is carried out during each operation of the brake in order to overcome the release play of the brake and to compensate the elasticities of the brake pads and the caliper arising when force is applied. Depending upon the amount of the actuating power and the size of the release play, it normally amounts to <4 mm.
In contrast, the wear stroke is the wear adjusting path which the caliper carries out over a large number of brake operations in order to compensate for the wear at the reaction side of the brake. The wear stroke is composed of the wear of the brake pad situated on the outside and the brake disc friction surface situated on the outside and normally amounts to up to 25 mm.
In comparison, in the case of the brake construction having a fixed caliper and a displaceable brake disc, the working stroke and the wear stroke are generated by displacing the brake disc.
The constructions with the sliding caliper or the hinged caliper have the disadvantage that a brake anchor plate fixed to the axle is required for absorbing the circumferential force of the brake pads and the holding and guiding of the caliper. This component causes additional cost and weight. In addition, the required slide-guiding or swivelling system is susceptible to disturbances.
In contrast, the construction with the displaceable brake disc has the problem of keeping the brake disc on the guiding area of the hub freely slidable over the entire service life. Because of the narrow installation conditions and the harsh environmental stress, an effective sealing can hardly be implemented.
In light of this background, the present invention begins with the concept of mutually combining the advantages of the above-described caliper concepts, in which case an easy adaptability of the disc brake should exist to various application devices.
The invention achieves this task by providing a disc brake, particularly for commercial vehicles, having a caliper straddling a brake disc, an application device arranged in the caliper for applying the brake, as well as an adjusting system arranged in the caliper for compensating brake pad and/or disc wear by adjusting the distance between the brake pad and the brake disc, wherein the adjusting system has at least one adjusting device. The caliper has a two-part construction including application-side and reaction-side caliper parts. The reaction-side caliper part is designed such that it straddles the brake disc in its upper circumferential area. The adjusting system has at least one or more adjusting devices also on the reaction side of the brake disc, and preferably on each side of the brake disc.
Accordingly, the caliper is constructed in two parts, including an application-side and a reaction-side caliper part, the reaction-side caliper part being further developed such that it frames or straddles the brake disc in its upper circumferential area.
Furthermore, the adjusting system has at least one or more adjusting devices also on the reaction side of the brake disc, or adjusting devices are provided on each side of the brake disc.
Since at least one or two adjusting devices for the separate displacing of the brake pads on both side of the brake disc is/are provided on each side of the brake disc, the path to be bridged by the caliper can clearly be reduced when the caliper is designed as a sliding or hinged caliper.
In contrast, in the case of a design as a fixed caliper, the displacement path of the brake disc on the axle can clearly be reduced.
In the manner of a construction kit, the reaction-side caliper part can be combined with various application-side caliper parts, which each may have different application devices; thus, for example, an application device with an eccentrically disposed rotary lever in the interior of the caliper, or an application device with one or more ball screws.
This module-type construction permits an optimal adaptability of the brake to different applications.
The module system can also be used for the adaptation to different wheel sizes. However, in this case, the respectively identical application-side caliper part, i.e., the application device housing, is combined with different reaction-side caliper parts.
In the case of an application device having a threaded spindle system of the type shown in FIG. 2, the screw system itself also forms the application-side adjusting device, in which case the rotating movement required for the adjustment can, in each case, take place in a manner known per se from S-cam drum brakes by way of a compressed-air cylinder and a brake lever constructed as a slack adjuster or an electric-motor drive.
By means of the invention, a disc brake in particular can be implemented in the case of which the generating of the reaction force on the side of the brake facing away from the application device takes place by                displacing the caliper and/or        swivelling the caliper and/or        displacing the brake disc,        deforming the caliper and/or the disc, and/orin which case, as a result of the displacing and/or swivelling and/or deforming movement, essentially only the path of half or the whole power stroke needs to be bridged.        
The invention combines the advantages of the fixed-caliper principle, e.g. a compact construction and implementation of the wear stroke by the actuating system, with the advantages of the reaction force principle.
Alternatively or in addition, it is also contemplated that the reaction force generation on the side of the brake facing away from the application device side takes place by an elastic deforming of the caliper and/or of the brake disc and/or of another element, in which case essentially only the path of half or the whole power stroke needs to be bridged by the deformation. In this case, bearings of the brake disc or of the caliper can advantageously be further, or even completely, eliminated. Elastic brake discs are known per se; such as from German Patent document DE 198 10 685 A1.
By providing additional adjusting device(s) on both sides of the disc brake, it becomes possible to further develop the brake such that a mobility, (preferably a displaceability and/or a swivellability of the caliper and/or the brake disc) still only has to be ensured which is dimensioned such that the working stroke can be bridged during brakings in order to apply the brake. In this manner, the slide bearings and/or pivot bearings and guides can be dimensioned to be correspondingly smaller and more cost-effective. In addition, it is ensured that a smooth operation remains guaranteed along the entire sliding or swivelling path since the latter is bridged during virtually every braking.
The brake disc is preferably constructed as a sliding disc, which is displaceably guided on a brake disc hub such that, as a result of the displacement, a sliding path can be implemented which is limited maximally to the power stroke (depending on the design, the path which can be bridged by the displacing and/or swivelling movement of the caliper, in the case of a commercial vehicle brake, amounts to less than 4–6 mm or even less than 3 mm).
As an alternative or in addition, the caliper may be constructed as a sliding caliper which has a sliding caliper, bearing fastenable directly to the axle flange and which is dimensioned such that a sliding path can be bridged which is limited to the power stroke.
As an alternative or in addition, the caliper can be constructed as a hinged caliper, which has a hinged-caliper bearing, which preferably can be fastened directly to the axle flange and can be bridged with the swivelling angle which displaces the caliper relative to the brake disc essentially by the amount of the power stroke.
In particular, the disc brake according to the invention makes it possible to continue to arrange the power-generating device—such as a compressed-air-operated and/or electric-motor-operated brake cylinder or an electric drive—only on one side of the brake.
Additional advantages are achieved within the scope of the invention.
A variant of the invention solves the problem of the common adjusting of the adjusting rotary drives on both sides of the disc brake. In this case, the adjuster rotary drives on both sides of the brake disc are mutually coupled by a synchronization device. The synchronization device is, preferably, constructed as a coupling mechanism or as an electronic coupling system.
According to another embodiment, which can also be considered independently, the brake of the above-mentioned type is further developed in the caliper has a one- or two-part construction and, if it is constructed in two parts, has an application-side and a reaction-side caliper part. The reaction-side caliper part straddles the brake disc in its upper circumferential area. The adjusting system has at least one adjusting device on the reaction side of the brake disc. The brake application device has one or more ball screw(s). Here, a construction of the brake application device as a ball screw, and a micro-displaceable caliper and/or disc solution, are mutually combined with a reaction-side adjustment in a constructionally compact manner.
In this case, the caliper is constructed in one or two parts and, if it is constructed in two parts, has an application-side and a reaction-side caliper part. The reaction-side caliper part straddles the brake disc in its upper circumferential area. In addition, the adjusting system has at least one adjusting device on the reaction side of the brake disc, and the brake application device has one or more balls screw(s).
Additional advantageous embodiments of the invention are described and claimed herein.